There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Find the missing number in the sequence below:

What do you answer even though it never asks you questions?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

How many triangles are there in the picture below?

There is a basket full of hats. Three are white and two are black. Three men, Tom, Tim, and Jim, each take a hat out of the basket and put it on their heads without seeing the hat they selected or the hats the other men selected. The men arrange themselves so Tom can see Tim and Jim’s hats, Tim can see Jim’s hat, and Jim can’t see anyone’s hat. Tom is asked what color his hat is and he says he doesn’t know. Tim is asked the same question, and he also doesn’t know. Finally, Jim is asked the question, and he does know. What colour is his hat?

If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

15 caves are arranged in a circle at the temple of doom. One of these caves has the treasure of gems and wealth. Each day the treasure keepers can move the treasure to an adjacent cave or can keep it in the same cave. Every day two treasure seekers visit the place and have enough time to enter any two caves of their choice.

How do the treasure seekers ensure that they find the treasure in the minimum number of possible days?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?